Method and assembly for forming components having an internal passage defined therein

ABSTRACT

A method of forming a component having an internal passage defined therein includes positioning a jacketed core with respect to a mold. The jacketed core includes a hollow structure that includes an interior portion shaped to define at least one interior passage feature of the internal passage. The jacketed core also includes an inner core disposed within the hollow structure and complementarily shaped by the interior portion of the hollow structure. The method also includes introducing a component material in a molten state into a cavity of the mold to form the component, such that the inner core defines the internal passage including the at least one interior passage feature defined therein.

BACKGROUND

The field of the disclosure relates generally to components having aninternal passage defined therein, and more particularly to forminginternal passages that include interior passage features.

Some components require an internal passage to be defined therein, forexample, in order to perform an intended function. For example, but notby way of limitation, some components, such as hot gas path componentsof gas turbines, are subjected to high temperatures. At least some suchcomponents have internal passages defined therein to receive a flow of acooling fluid, such that the components are better able to withstand thehigh temperatures. For another example, but not by way of limitation,some components are subjected to friction at an interface with anothercomponent. At least some such components have internal passages definedtherein to receive a flow of a lubricant to facilitate reducing thefriction.

Moreover, a performance of at least some such internal passages isimproved by the addition of interior passage features, that is,structural features that extend within the passage and alter fluid flowwithin the passage, as compared to fluid flow within an otherwisesimilar, but substantially smooth-walled, passage. As just one example,interior passage features that extend inward from a wall of suchpassages may be used to turbulate a flow of a cooling fluid flowedthrough the passage, such that a thermal boundary layer proximate thepassage wall is disrupted and heat transfer efficiency is improved.

At least some known components having an internal passage definedtherein are formed in a mold, with a core of ceramic material extendingwithin the mold cavity at a location selected for the internal passage.After a molten metal alloy is introduced into the mold cavity around theceramic core and cooled to form the component, the ceramic core isremoved, such as by chemical leaching, to form the internal passage. Oneknown approach to creating interior passage features is to formcomplementary features on a surface of the ceramic core prior to formingthe component in the mold. However, at least some known ceramic coresare fragile, resulting in cores that are difficult and expensive toproduce and handle without damage. In particular, the addition ofcomplementary surface features on the core introduces stressconcentrations that increase a risk of cracking of the ceramic core.Another approach is to add the interior passage features after thecomponent is formed in the mold, for example, by using anelectrochemical process to shape the passage wall. However, at leastsome such post-forming processes are relatively time-consuming andexpensive. Moreover, with respect to both known approaches, ageometrical complexity of the interior passage features that can beformed is substantially limited.

BRIEF DESCRIPTION

In one aspect, a method of forming a component having an internalpassage defined therein is provided. The method includes positioning ajacketed core with respect to a mold. The jacketed core includes ahollow structure that includes an interior portion shaped to define atleast one interior passage feature of the internal passage. The jacketedcore also includes an inner core disposed within the hollow structureand complementarily shaped by the interior portion of the hollowstructure. The method also includes introducing a component material ina molten state into a cavity of the mold to form the component, suchthat the inner core defines the internal passage including the at leastone interior passage feature defined therein.

In another aspect, a mold assembly for use in forming a component havingan internal passage defined therein is provided. The mold assemblyincludes a mold defining a mold cavity therein, and a jacketed corepositioned with respect to the mold. The jacketed core includes a hollowstructure that includes an interior portion shaped to define at leastone interior passage feature of the internal passage. The jacketed corealso includes an inner core disposed within the hollow structure andcomplementarily shaped by the interior portion of the hollow structure,such that the inner core is configured to define the internal passageand the at least one interior passage feature defined therein when thecomponent is formed in the mold.

DRAWINGS

FIG. 1 is a schematic diagram of an exemplary rotary machine;

FIG. 2 is a schematic perspective view of an exemplary component for usewith the rotary machine shown in FIG. 1;

FIG. 3 is a schematic perspective view of an exemplary mold assembly formaking the component shown in FIG. 2, the mold assembly including ajacketed core positioned with respect to a mold;

FIG. 4 is a schematic cross-section of an exemplary jacketed core foruse with the mold assembly shown in FIG. 3, taken along lines 4-4 shownin FIG. 3;

FIG. 5 is a schematic perspective view of a portion of another exemplarycomponent for use with the rotary machine shown in FIG. 1, the componentincluding an internal passage having a plurality of interior passagefeatures;

FIG. 6 is a schematic perspective cutaway view of another exemplaryjacketed core for use with the mold assembly shown in FIG. 3 to form thecomponent having interior passage features as shown in FIG. 5;

FIG. 7 is a schematic illustration of an exemplary straight tube, anexemplary hollow structure (shown in cut-away view) formed from theexemplary straight tube, and an exemplary jacketed core (shown incut-away view) formed from the hollow structure and for use with themold assembly shown in FIG. 3;

FIG. 8 is a schematic perspective view of a portion of another exemplarycomponent for use with the rotary machine shown in FIG. 1, the componentincluding an internal passage having a contoured cross-section;

FIG. 9 is a schematic perspective cutaway view of another exemplaryjacketed core for use with the mold assembly shown in FIG. 3 to form thecomponent having the internal passage shown in FIG. 9;

FIG. 10 is a schematic perspective cutaway view of three additionalexemplary embodiments of a jacketed core for use with the mold assemblyshown in FIG. 3;

FIG. 11 is a schematic cross-sectional side view of another exemplaryhollow structure for use in forming a jacketed core for use with themold assembly shown in FIG. 3;

FIG. 12 is a schematic front cross-section view of the hollow structureshown in FIG. 11, taken along lines 12-12 shown in FIG. 11;

FIG. 13 is a flow diagram of an exemplary method of forming a componenthaving an internal passage defined therein, such as a component for usewith the rotary machine shown in FIG. 1; and

FIG. 14 is a continuation of the flow diagram from FIG. 13.

DETAILED DESCRIPTION

In the following specification and the claims, reference will be made toa number of terms, which shall be defined to have the followingmeanings.

The singular forms “a”, “an”, and “the” include plural references unlessthe context clearly dictates otherwise.

“Optional” or “optionally” means that the subsequently described eventor circumstance may or may not occur, and that the description includesinstances where the event occurs and instances where it does not.

Approximating language, as used herein throughout the specification andclaims, may be applied to modify any quantitative representation thatcould permissibly vary without resulting in a change in the basicfunction to which it is related. Accordingly, a value modified by a termor terms such as “about,” “approximately,” and “substantially” is not tobe limited to the precise value specified. In at least some instances,the approximating language may correspond to the precision of aninstrument for measuring the value. Here and throughout thespecification and claims, range limitations may be identified. Suchranges may be combined and/or interchanged, and include all thesub-ranges contained therein unless context or language indicatesotherwise.

The exemplary components and methods described herein overcome at leastsome of the disadvantages associated with known assemblies and methodsfor forming a component having an internal passage that includesinterior passage features defined therein. The embodiments describedherein provide a jacketed core positioned with respect to a mold. Thejacketed core includes a hollow structure and an inner core disposedwithin the hollow structure. The inner core extends within the moldcavity to define a position of the internal passage within the componentto be formed in the mold. The hollow structure is substantiallyabsorbable by a component material introduced into the mold cavity toform the component. An interior portion of the hollow structure isshaped to define complementary features of the inner core, such that thecomplementary inner core features define the interior passage featureswhen the component is formed.

FIG. 1 is a schematic view of an exemplary rotary machine 10 havingcomponents for which embodiments of the current disclosure may be used.In the exemplary embodiment, rotary machine 10 is a gas turbine thatincludes an intake section 12, a compressor section 14 coupleddownstream from intake section 12, a combustor section 16 coupleddownstream from compressor section 14, a turbine section 18 coupleddownstream from combustor section 16, and an exhaust section 20 coupleddownstream from turbine section 18. A generally tubular casing 36 atleast partially encloses one or more of intake section 12, compressorsection 14, combustor section 16, turbine section 18, and exhaustsection 20. In alternative embodiments, rotary machine 10 is any rotarymachine for which components formed with internal passages havinginterior passage features as described herein are suitable. Moreover,although embodiments of the present disclosure are described in thecontext of a rotary machine for purposes of illustration, it should beunderstood that the embodiments described herein are applicable in anycontext that involves a component suitably formed with an internalpassage having interior passage features defined therein.

In the exemplary embodiment, turbine section 18 is coupled to compressorsection 14 via a rotor shaft 22. It should be noted that, as usedherein, the term “couple” is not limited to a direct mechanical,electrical, and/or communication connection between components, but mayalso include an indirect mechanical, electrical, and/or communicationconnection between multiple components.

During operation of gas turbine 10, intake section 12 channels airtowards compressor section 14. Compressor section 14 compresses the airto a higher pressure and temperature. More specifically, rotor shaft 22imparts rotational energy to at least one circumferential row ofcompressor blades 40 coupled to rotor shaft 22 within compressor section14. In the exemplary embodiment, each row of compressor blades 40 ispreceded by a circumferential row of compressor stator vanes 42extending radially inward from casing 36 that direct the air flow intocompressor blades 40. The rotational energy of compressor blades 40increases a pressure and temperature of the air. Compressor section 14discharges the compressed air towards combustor section 16.

In combustor section 16, the compressed air is mixed with fuel andignited to generate combustion gases that are channeled towards turbinesection 18. More specifically, combustor section 16 includes at leastone combustor 24, in which a fuel, for example, natural gas and/or fueloil, is injected into the air flow, and the fuel-air mixture is ignitedto generate high temperature combustion gases that are channeled towardsturbine section 18.

Turbine section 18 converts the thermal energy from the combustion gasstream to mechanical rotational energy. More specifically, thecombustion gases impart rotational energy to at least onecircumferential row of rotor blades 70 coupled to rotor shaft 22 withinturbine section 18. In the exemplary embodiment, each row of rotorblades 70 is preceded by a circumferential row of turbine stator vanes72 extending radially inward from casing 36 that direct the combustiongases into rotor blades 70. Rotor shaft 22 may be coupled to a load (notshown) such as, but not limited to, an electrical generator and/or amechanical drive application. The exhausted combustion gases flowdownstream from turbine section 18 into exhaust section 20. Componentsof rotary machine 10 are designated as components 80. Components 80proximate a path of the combustion gases are subjected to hightemperatures during operation of rotary machine 10. Additionally oralternatively, components 80 include any component suitably formed withan internal passage having interior passage features defined therein.

FIG. 2 is a schematic perspective view of an exemplary component 80,illustrated for use with rotary machine 10 (shown in FIG. 1). Component80 includes at least one internal passage 82 defined therein. Forexample, a cooling fluid is provided to internal passage 82 duringoperation of rotary machine 10 to facilitate maintaining component 80below a temperature of the hot combustion gases. Although only oneinternal passage 82 is illustrated, it should be understood thatcomponent 80 includes any suitable number of internal passages 82 formedas described herein.

Component 80 is formed from a component material 78. In the exemplaryembodiment, component material 78 is a suitable nickel-based superalloy.In alternative embodiments, component material 78 is at least one of acobalt-based superalloy, an iron-based alloy, and a titanium-basedalloy. In other alternative embodiments, component material 78 is anysuitable material that enables component 80 to be formed as describedherein.

In the exemplary embodiment, component 80 is one of rotor blades 70 orstator vanes 72. In alternative embodiments, component 80 is anothersuitable component of rotary machine 10 that is capable of being formedwith an internal passage having interior passage features as describedherein. In still other embodiments, component 80 is any component forany suitable application that is suitably formed with an internalpassage having interior passage features defined therein.

In the exemplary embodiment, rotor blade 70, or alternatively statorvane 72, includes a pressure side 74 and an opposite suction side 76.Each of pressure side 74 and suction side 76 extends from a leading edge84 to an opposite trailing edge 86. In addition, rotor blade 70, oralternatively stator vane 72, extends from a root end 88 to an oppositetip end 90, defining a blade length 96. In alternative embodiments,rotor blade 70, or alternatively stator vane 72, has any suitableconfiguration that is capable of being formed with an internal passageas described herein.

In certain embodiments, blade length 96 is at least about 25.4centimeters (cm) (10 inches). Moreover, in some embodiments, bladelength 96 is at least about 50.8 cm (20 inches). In particularembodiments, blade length 96 is in a range from about 61 cm (24 inches)to about 101.6 cm (40 inches). In alternative embodiments, blade length96 is less than about 25.4 cm (10 inches). For example, in someembodiments, blade length 96 is in a range from about 2.54 cm (1 inch)to about 25.4 cm (10 inches). In other alternative embodiments, bladelength 96 is greater than about 101.6 cm (40 inches).

In the exemplary embodiment, internal passage 82 extends from root end88 to tip end 90. In alternative embodiments, internal passage 82extends within component 80 in any suitable fashion, and to any suitableextent, that enables internal passage 82 to be formed as describedherein. In certain embodiments, internal passage 82 is nonlinear. Forexample, component 80 is formed with a predefined twist along an axis 89defined between root end 88 and tip end 90, and internal passage 82 hasa curved shape complementary to the axial twist. In some embodiments,internal passage 82 is positioned at a substantially constant distance94 from pressure side 74 along a length of internal passage 82.Alternatively or additionally, a chord of component 80 tapers betweenroot end 88 and tip end 90, and internal passage 82 extends nonlinearlycomplementary to the taper, such that internal passage 82 is positionedat a substantially constant distance 92 from trailing edge 86 along thelength of internal passage 82. In alternative embodiments, internalpassage 82 has a nonlinear shape that is complementary to any suitablecontour of component 80. In other alternative embodiments, internalpassage 82 is nonlinear and other than complementary to a contour ofcomponent 80. In some embodiments, internal passage 82 having anonlinear shape facilitates satisfying a preselected cooling criterionfor component 80. In alternative embodiments, internal passage 82extends linearly.

In some embodiments, internal passage 82 has a substantially circularcross-sectional perimeter. In alternative embodiments, internal passage82 has a substantially ovoid cross-sectional perimeter. In otheralternative embodiments, internal passage 82 has any suitably shapedcross-sectional perimeter that enables internal passage 82 to be formedas described herein. Moreover, in certain embodiments, a shape of thecross-sectional perimeter of internal passage 82 is substantiallyconstant along a length of internal passage 82. In alternativeembodiments, the shape of the cross-sectional perimeter of internalpassage 82 varies along a length of internal passage 82 in any suitablefashion that enables internal passage 82 to be formed as describedherein.

FIG. 3 is a schematic perspective view of a mold assembly 301 for makingcomponent 80 (shown in FIG. 2). Mold assembly 301 includes a jacketedcore 310 positioned with respect to a mold 300. FIG. 4 is a schematiccross-section of jacketed core 310 taken along lines 4-4 shown in FIG.3. With reference to FIGS. 2-4, an interior wall 302 of mold 300 definesa mold cavity 304. Interior wall 302 defines a shape corresponding to anexterior shape of component 80, such that component material 78 in amolten state can be introduced into mold cavity 304 and cooled to formcomponent 80. It should be recalled that, although component 80 in theexemplary embodiment is rotor blade 70, or alternatively stator vane 72,in alternative embodiments component 80 is any component suitablyformable with an internal passage having interior passage featuresdefined therein, as described herein.

Jacketed core 310 is positioned with respect to mold 300 such that aportion 315 of jacketed core 310 extends within mold cavity 304.Jacketed core 310 includes a hollow structure 320 formed from a firstmaterial 322, and an inner core 324 disposed within hollow structure 320and formed from an inner core material 326. Inner core 324 is shaped todefine a shape of internal passage 82, and inner core 324 of portion 315of jacketed core 310 positioned within mold cavity 304 defines aposition of internal passage 82 within component 80.

Hollow structure 320 includes an outer wall 380 that substantiallyencloses inner core 324 along a length of inner core 324. An interiorportion 360 of hollow structure 320 is located interiorly with respectto outer wall 380, such that inner core 324 is complementarily shaped byinterior portion 360 of hollow structure 320. In certain embodiments,hollow structure 320 defines a generally tubular shape. For example, butnot by way of limitation, hollow structure 320 is initially formed froma substantially straight metal tube that is suitably manipulated into anonlinear shape, such as a curved or angled shape, as necessary todefine a selected nonlinear shape of inner core 324 and, thus, ofinternal passage 82. In alternative embodiments, hollow structure 320defines any suitable shape that enables inner core 324 to define a shapeof internal passage 82 as described herein.

In the exemplary embodiment, hollow structure 320 has a wall thickness328 that is less than a characteristic width 330 of inner core 324.Characteristic width 330 is defined herein as the diameter of a circlehaving the same cross-sectional area as inner core 324. In alternativeembodiments, hollow structure 320 has a wall thickness 328 that is otherthan less than characteristic width 330. A shape of a cross-sectionalperimeter of inner core 324 is circular in the exemplary embodimentshown in FIGS. 3 and 4. Alternatively, the shape of the cross-sectionalperimeter of inner core 324 corresponds to any suitable cross-sectionalperimeter of internal passage 82 that enables internal passage 82 tofunction as described herein.

Mold 300 is formed from a mold material 306. In the exemplaryembodiment, mold material 306 is a refractory ceramic material selectedto withstand a high temperature environment associated with the moltenstate of component material 78 used to form component 80. In alternativeembodiments, mold material 306 is any suitable material that enablescomponent 80 to be formed as described herein. Moreover, in theexemplary embodiment, mold 300 is formed by a suitable investmentcasting process. For example, but not by way of limitation, a suitablepattern material, such as wax, is injected into a suitable pattern dieto form a pattern (not shown) of component 80, the pattern is repeatedlydipped into a slurry of mold material 306 which is allowed to harden tocreate a shell of mold material 306, and the shell is dewaxed and firedto form mold 300. In alternative embodiments, mold 300 is formed by anysuitable method that enables mold 300 to function as described herein.

In certain embodiments, jacketed core 310 is secured relative to mold300 such that jacketed core 310 remains fixed relative to mold 300during a process of forming component 80. For example, jacketed core 310is secured such that a position of jacketed core 310 does not shiftduring introduction of molten component material 78 into mold cavity 304surrounding jacketed core 310. In some embodiments, jacketed core 310 iscoupled directly to mold 300. For example, in the exemplary embodiment,a tip portion 312 of jacketed core 310 is rigidly encased in a tipportion 314 of mold 300. Additionally or alternatively, a root portion316 of jacketed core 310 is rigidly encased in a root portion 318 ofmold 300 opposite tip portion 314. For example, but not by way oflimitation, mold 300 is formed by investment casting as described above,and jacketed core 310 is securely coupled to the suitable pattern diesuch that tip portion 312 and root portion 316 extend out of the patterndie, while portion 315 extends within a cavity of the die. The patternmaterial is injected into the die around jacketed core 310 such thatportion 315 extends within the pattern. The investment casting causesmold 300 to encase tip portion 312 and/or root portion 316. Additionallyor alternatively, jacketed core 310 is secured relative to mold 300 inany other suitable fashion that enables the position of jacketed core310 relative to mold 300 to remain fixed during a process of formingcomponent 80.

First material 322 is selected to be at least partially absorbable bymolten component material 78. In certain embodiments, component material78 is an alloy, and first material 322 is at least one constituentmaterial of the alloy. For example, in the exemplary embodiment,component material 78 is a nickel-based superalloy, and first material322 is substantially nickel, such that first material 322 issubstantially absorbable by component material 78 when componentmaterial 78 in the molten state is introduced into mold cavity 304. Inalternative embodiments, component material 78 is any suitable alloy,and first material 322 is at least one material that is at leastpartially absorbable by the molten alloy. For example, componentmaterial 78 is a cobalt-based superalloy, and first material 322 issubstantially cobalt. For another example, component material 78 is aniron-based alloy, and first material 322 is substantially iron. Foranother example, component material 78 is a titanium-based alloy, andfirst material 322 is substantially titanium.

In certain embodiments, wall thickness 328 is sufficiently thin suchthat first material 322 of portion 315 of jacketed core 310, that is,the portion that extends within mold cavity 304, is substantiallyabsorbed by component material 78 when component material 78 in themolten state is introduced into mold cavity 304. For example, in somesuch embodiments, first material 322 is substantially absorbed bycomponent material 78 such that no discrete boundary delineates hollowstructure 320 from component material 78 after component material 78 iscooled. Moreover, in some such embodiments, first material 322 issubstantially absorbed such that, after component material 78 is cooled,first material 322 is substantially uniformly distributed withincomponent material 78. For example, a concentration of first material322 proximate inner core 324 is not detectably higher than aconcentration of first material 322 at other locations within component80. For example, and without limitation, first material 322 is nickeland component material 78 is a nickel-based superalloy, and nodetectable higher nickel concentration remains proximate inner core 324after component material 78 is cooled, resulting in a distribution ofnickel that is substantially uniform throughout the nickel-basedsuperalloy of formed component 80.

In alternative embodiments, wall thickness 328 is selected such thatfirst material 322 is other than substantially absorbed by componentmaterial 78. For example, in some embodiments, after component material78 is cooled, first material 322 is other than substantially uniformlydistributed within component material 78. For example, a concentrationof first material 322 proximate inner core 324 is detectably higher thana concentration of first material 322 at other locations withincomponent 80. In some such embodiments, first material 322 is partiallyabsorbed by component material 78 such that a discrete boundarydelineates hollow structure 320 from component material 78 aftercomponent material 78 is cooled. Moreover, in some such embodiments,first material 322 is partially absorbed by component material 78 suchthat at least a portion of hollow structure 320 proximate inner core 324remains intact after component material 78 is cooled.

In the exemplary embodiment, inner core material 326 is a refractoryceramic material selected to withstand a high temperature environmentassociated with the molten state of component material 78 used to formcomponent 80. For example, but without limitation, inner core material326 includes at least one of silica, alumina, and mullite. Moreover, inthe exemplary embodiment, inner core material 326 is selectivelyremovable from component 80 to form internal passage 82. For example,but not by way of limitation, inner core material 326 is removable fromcomponent 80 by a suitable process that does not substantially degradecomponent material 78, such as, but not limited to, a suitable chemicalleaching process. In certain embodiments, inner core material 326 isselected based on a compatibility with, and/or a removability from,component material 78. In alternative embodiments, inner core material326 is any suitable material that enables component 80 to be formed asdescribed herein.

In some embodiments, jacketed core 310 is formed by filling hollowstructure 320 with inner core material 326. For example, but not by wayof limitation, inner core material 326 is injected as a slurry intohollow structure 320, and inner core material 326 is dried within hollowstructure 320 to form jacketed core 310. Moreover, in certainembodiments, hollow structure 320 substantially structurally reinforcesinner core 324, thus reducing potential problems that would beassociated with production, handling, and use of an unreinforced innercore 324 to form component 80 in some embodiments. For example, incertain embodiments, inner core 324 is a relatively brittle ceramicmaterial subject to a relatively high risk of fracture, cracking, and/orother damage. Thus, in some such embodiments, forming and transportingjacketed core 310 presents a much lower risk of damage to inner core324, as compared to using an unjacketed inner core 324. Similarly, insome such embodiments, forming a suitable pattern around jacketed core310 to be used for investment casting of mold 300, such as by injectinga wax pattern material into a pattern die around jacketed core 310,presents a much lower risk of damage to inner core 324, as compared tousing an unjacketed inner core 324. Thus, in certain embodiments, use ofjacketed core 310 presents a much lower risk of failure to produce anacceptable component 80 having internal passage 82 defined therein, ascompared to the same steps if performed using an unjacketed inner core324 rather than jacketed core 310. Thus, jacketed core 310 facilitatesobtaining advantages associated with positioning inner core 324 withrespect to mold 300 to define internal passage 82, while reducing oreliminating fragility problems associated with inner core 324. Inalternative embodiments, hollow structure 320 does not substantiallystructurally reinforce inner core 324.

For example, in certain embodiments, such as, but not limited to,embodiments in which component 80 is rotor blade 70, characteristicwidth 330 of inner core 324 is within a range from about 0.050 cm (0.020inches) to about 1.016 cm (0.400 inches), and wall thickness 328 ofhollow structure 320 is selected to be within a range from about 0.013cm (0.005 inches) to about 0.254 cm (0.100 inches). More particularly,in some such embodiments, characteristic width 330 is within a rangefrom about 0.102 cm (0.040 inches) to about 0.508 cm (0.200 inches), andwall thickness 328 is selected to be within a range from about 0.013 cm(0.005 inches) to about 0.038 cm (0.015 inches). For another example, insome embodiments, such as, but not limited to, embodiments in whichcomponent 80 is a stationary component, such as but not limited tostator vane 72, characteristic width 330 of inner core 324 is greaterthan about 1.016 cm (0.400 inches), and/or wall thickness 328 isselected to be greater than about 0.254 cm (0.100 inches). Inalternative embodiments, characteristic width 330 is any suitable valuethat enables the resulting internal passage 82 to perform its intendedfunction, and wall thickness 328 is selected to be any suitable valuethat enables jacketed core 310 to function as described herein.

Moreover, in certain embodiments, prior to introduction of inner corematerial 326 within hollow structure 320 to form jacketed core 310,hollow structure 320 is pre-formed to correspond to a selected nonlinearshape of internal passage 82. For example, first material 322 is ametallic material that is relatively easily shaped prior to filling withinner core material 326, thus reducing or eliminating a need toseparately form and/or machine inner core 324 into a nonlinear shape.Moreover, in some such embodiments, the structural reinforcementprovided by hollow structure 320 enables subsequent formation andhandling of inner core 324 in a non-linear shape that would be difficultto form and handle as an unjacketed inner core 324. Thus, jacketed core310 facilitates formation of internal passage 82 having a curved and/orotherwise non-linear shape of increased complexity, and/or with adecreased time and cost. In certain embodiments, hollow structure 320 ispre-formed to correspond to the nonlinear shape of internal passage 82that is complementary to a contour of component 80. For example, but notby way of limitation, component 80 is one of rotor blade 70 and statorvane 72, and hollow structure 320 is pre-formed in a shape complementaryto at least one of an axial twist and a taper of component 80, asdescribed above.

FIG. 5 is a schematic perspective view of a portion of another exemplarycomponent 80 that includes internal passage 82 having a plurality ofinterior passage features 98. FIG. 6 is a schematic perspective cutawayview of another exemplary jacketed core 310 for use in mold assembly 301to form component 80 having interior passage features 98 as shown inFIG. 5. In particular, a portion of hollow structure 320 is cut away inthe view of FIG. 6 to illustrate features of inner core 324. Withreference to FIGS. 5 and 6, internal passage 82 is generally defined byan interior wall 100 of component 80, and interior passage features 98are shaped to define local variations in a flow path defined by internalpassage 82. For example, but not by way of limitation, interior passagefeatures 98 are turbulators that extend radially inward from interiorwall 100 generally towards a center of internal passage 82, and areshaped to disrupt a thermal boundary layer flow along interior wall 100to improve a heat transfer capability of a cooling fluid provided tointernal passage 82 during operation of rotary machine 10 (shown in FIG.1). Alternatively, interior passage features 98 are any structure shapedto define local variations in the flow path defined by internal passage82.

As discussed above, the shape of inner core 324 defines the shape ofinternal passage 82. In certain embodiments, inner core 324 iscomplementarily shaped by interior portion 360 of hollow structure 320such that inner core 324 defines internal passage 82 including at leastone interior passage feature 98 defined therein. For example, inner core324 is complementarily shaped by interior portion 360 to include atleast one complementary feature 331, and the at least one complementaryfeature 331 has a shape complementary to a shape of at least oneinterior passage feature 98. Thus, when molten component material 78 isintroduced into mold cavity 304 (shown in FIG. 3) surrounding jacketedcore 310 and first material 322 is absorbed into molten componentmaterial 78, component material 78 in the molten state couples againstthe at least one complementary feature 331 to form the at least oneinterior passage feature 98. Additionally or alternatively, to an extentthat a portion of interior portion 360 of hollow structure 320 adjacentinner core 324 remains intact after molten component material 78 isintroduced into mold cavity 304 and cooled, the intact portion ofinterior portion 360 coupled against the at least one complementaryfeature 331 defines the at least one interior passage feature 98.

For example, in the illustrated embodiment, the at least onecomplementary feature 331 is a plurality of recessed features 334defined in an exterior surface 332 of inner core 324. Each recessedfeature 334 has a shape complementary to a shape of a correspondinginterior passage feature 98, such that when molten component material 78is introduced into mold cavity 304 and first material 322 is absorbedinto molten component material 78, molten component material 78 fillsthe plurality of recessed features 334. Cooled component material 78within recessed features 334 forms the plurality of interior passagefeatures 98 after inner core 324 is removed, such as, but not limitedto, by using a chemical leaching process. For example, each recessedfeature 334 is defined with a depth 336 and a width 338, and eachcorresponding interior passage feature 98 is formed as a ridge extendinginteriorly from interior wall 100, with a ridge height 102 substantiallyequal to depth 336 and a ridge width 104 substantially equal to width338. Thus, exterior surface 332 defines a general shape of interior wall100, and complementary features 331 of inner core 324 define a shape ofinterior passage features 98 of internal passage 82.

In some embodiments, the shaping of interior portion 360 of hollowstructure 320 to define interior passage features 98 during formation ofcomponent 80 in mold 300 enables the formation of interior passagefeatures 98 at locations along internal passage 82 that could not beconsistently and reliably formed using other methods. For example, innercore material 326 is a relatively brittle ceramic material, andindependently shaping a similar, but unjacketed, inner core 324 todefine complementary features 331 increases a risk of cracking orfracturing inner core 324. The risk is further increased for anunjacketed inner core 324 having a large length-to-diameter (L/d) ratioand/or a substantially nonlinear shape. For another example, addinginterior passage features 98 along a length of internal passage 82 in asubsequent separate process, that is, after component 80 is formed isrelatively difficult to achieve with repeatability and precision, andparticularly so for internal passages 82 having a largelength-to-diameter (L/d) ratio and/or a substantially nonlinear shape.

In certain embodiments, interior portion 360 of hollow structure 320 ispre-formed to complementarily shape inner core 324, and thus to define aselected shape of interior passage features 98, prior to disposing innercore material 326 within hollow structure 320. For example, hollowstructure 320 is crimped at a plurality of locations to define aplurality of indentations 340, and each indentation 340 causes interiorportion 360 of hollow structure 320 to define a corresponding recessedfeature 334 when hollow structure 320 is filled with inner core material326. For example, a depth 342 of each indentation 340, in cooperationwith wall thickness 328, defines depth 336 of the corresponding recessedfeature 334.

In the illustrated embodiment, each indentation 340 is defined as agroove that extends circumferentially around outer wall 380 of hollowstructure 320, such that each recessed feature 334 is correspondinglydefined as a groove that extends circumferentially around inner core324. In turn, each recessed feature 334 defines a corresponding interiorpassage feature 98 as a ridge that extends circumferentially around aperimeter of internal passage 82 when component 80 is formed. Inalternative embodiments, each indentation 340 has a shape selected toform any suitable shape for each corresponding recessed feature 334 andinterior passage feature 98.

FIG. 7 is a schematic illustration of an exemplary straight tube 319,formed from first material 322 and having a generally circularcross-section, an exemplary hollow structure 320 (shown in cut-awayview) formed from straight tube 319, and an exemplary jacketed core 310(shown in cut-away view) formed from hollow structure 320 and for usewith mold assembly 301 (shown in FIG. 3). In the illustrated embodiment,hollow structure 320 has a nonlinear shape along its length. Forexample, but not by way of limitation, the nonlinear shape is configuredto match a shape of internal passage 82 having a curved shapecomplementary to a shape of component 80 (shown in FIG. 2). Hollowstructure 320 also includes interior portion 360 shaped to define atleast one interior passage feature 98 (not shown) of the correspondinginternal passage 82. Interior portion 360 defines at least onecomplementary feature 331 of inner core 324.

More specifically, in the illustrated embodiment, hollow structure 320includes indentations 340 formed as dimples pressed into outer wall 380of hollow structure 320. Each indentation 340 forms a correspondingprotrusion 341 on interior portion 360 of hollow structure 320. Wheninner core material 326 is disposed within hollow structure 320 to formjacketed core 310, protrusions 341 form complementary features 331 asdimple imprints 333 in inner core 324. Complementary features 331 arethus configured to form interior passage features 98 within passage 82(shown in FIG. 2) shaped substantially identically to protrusions 341.Although interior portion 360 is illustrated as having protrusions 341,in alternative embodiments, interior portion 360 is shaped in anysuitable fashion to define a selected shape of complementary features331 and of interior passage features 98.

In some embodiments, shaping hollow structure 320 to define the selectedshape of complementary features 331 prior to disposing inner corematerial 326 within hollow structure 320 reduces potential problemsassociated with forming complementary features 331 after jacketed core310 is formed. For example, inner core material 326 is a relativelybrittle ceramic material, such that a relatively high risk of fracture,cracking, and/or other damage to inner core 324 would be presented bymachining or otherwise manipulating jacketed core 310 directly to formcomplementary features 331. Thus, shaping hollow structure 320 to definethe selected shape of complementary features 331 prior to disposinginner core material 326 within hollow structure 320 facilitates forminginterior passage features 98 integrally with internal passage 82, whilereducing or eliminating fragility problems associated with inner core324.

In certain embodiments, hollow structure 320 having at least one of (i)a nonlinear shape along its length and (ii) an interior portion 360shaped to define at least one interior passage feature 98 is formed fromstraight tube 319 using a suitable tube press (not shown). For example,a die is configured to press-bend straight tube 319 to match apreselected nonlinear shape of internal passage 82, and the die surfaceincludes protrusions configured to substantially simultaneously form apreselected pattern of indentations 340 on hollow structure 320. In somesuch embodiments, straight tube 319 is a standard orcommercial-off-the-shelf item, reducing a cost of manufacture of hollowstructure 320. Moreover, in some such embodiments, a one-step press-bendmanufacture further facilitates increased speed and decreased cost ofmanufacture of hollow structure 320. In alternative embodiments, anysuitable tube-bending process and/or interior portion-forming process,including multiple-step processes, is used to form hollow structure 320from straight tube 319.

Additionally, in some such embodiments, the press-bend process isconfigured to selectively transform a circular cross-sectional perimeterof at least a portion of straight tube 319 into a selected non-circularcross-sectional perimeter of at least a portion of hollow structure 320.For example, in some embodiments, a press die is configured toplastically deform the circular cross-sectional perimeter of straighttube 319 into an ovoid cross-sectional perimeter of hollow structure320. In some embodiments, the ovoid cross-sectional perimeter provides avisual cue for proper orientation of jacketed core 310 relative to mold300 to form mold assembly 301 (shown in FIG. 3). Moreover, in someembodiments, a corresponding preselected ovoid cross-sectional perimeterof internal passage 82 provides improved cooling performance proximatetrailing edge 86 of rotor blade 70.

In alternative embodiments, hollow structure 320 is formed in a selectednonlinear shape by coupling together a plurality of longitudinalsegments (not shown), wherein each segment is individually pre-formed,such as from a respective straight tube 319, to define a shape and/or apreselected pattern of interior passage features 98 of a correspondingsegment of internal passage 82. In other alternative embodiments, hollowstructure 320 is formed with a selected non-circular cross-sectionalperimeter by coupling together a suitable plurality of longitudinallyextending partial perimeter sections, such as a pair of half-perimetersections, along longitudinal seams (not shown), wherein each partialperimeter section is pre-formed, such as from a respective blank ofsheet metal (not shown), to define a non-circular cross-sectionalperimeter and/or a preselected pattern of interior passage features 98of internal passage 82. In other alternative embodiments, any suitablemanufacturing process, including combination or multiple-step processes,is used to form hollow structure 320 having a nonlinear shape and/ornon-circular cross-section and/or preselected pattern of interiorpassage features 98.

For another example, FIG. 8 is a schematic perspective view of a portionof another exemplary component 80 that includes internal passage 82having a non-circular cross-sectional perimeter. FIG. 9 is a schematicperspective cutaway view of another exemplary jacketed core 310 for usewith mold assembly 301 to form component 80 having internal passage 82as shown in FIG. 8. In particular, a portion of hollow structure 320 iscut away in the view of FIG. 9 to illustrate features of inner core 324.

With reference to FIGS. 8 and 9, in the exemplary embodiment, component80 is one of rotor blade 70 and stator vane 72, and internal passage 82is defined in component 80 proximate trailing edge 86. Morespecifically, internal passage 82 is defined by interior wall 100 ofcomponent 80 to have a contoured cross-sectional perimeter correspondingto a tapered geometry of trailing edge 86. Interior passage features 98are defined along opposing elongated edges 110 of internal passage 82 tofunction as turbulators, and extend inward from interior wall 100towards a center of internal passage 82. Although interior passagefeatures 98 are illustrated as a repeating pattern of elongated ridgeseach transverse to an axial direction of internal passage 82, it shouldbe understood that in alternative embodiments, interior passage features98 have any suitable shape, orientation, and/or pattern that enablesinternal passage 82 to function for its intended purpose.

As discussed above, the shape of exterior surface 332 and complementaryfeatures 331 of inner core 324 define the shape of interior wall 100 andinterior passage features 98 of internal passage 82. More specifically,inner core 324 has an elongated, tapered cross-sectional perimetercorresponding to the contoured cross-sectional perimeter of internalpassage 82. Complementary features 331 are implemented as recessedfeatures 334. In the exemplary embodiment, recessed features 334 aredefined as elongated notches 352 in opposing elongated sides 346 ofexterior surface 332, and have a shape complementary to a shape ofinterior passage features 98, as described above. In alternativeembodiments, component 80 has any suitable geometry, and inner core 324is shaped to form internal passage 82 having any suitable shape thatsuitably corresponds to the geometry of component 80.

In certain embodiments, hollow structure 320 is pre-formed in a suitablepress-bend process, as described above, to selectively transform acircular cross-sectional perimeter of at least a portion of straighttube 319 (shown in FIG. 7) into the selected non-circularcross-sectional perimeter of hollow structure 320, prior to disposinginner core material 326 within hollow structure 320. More specifically,the non-circular cross-sectional perimeter of hollow structure 320 isselected to define the corresponding shape of exterior surface 332 ofinner core 324, and thus to define the selected contouredcross-sectional perimeter of internal passage 82. In addition, thepress-bend process shapes interior portion 360 of hollow structure 320to define interior passage features 98. More specifically, thepress-bend process crimps straight tube 319 at a plurality of locationsto define a plurality of indentations 340 in outer wall 380 of hollowstructure 320, and each indentation 340 defines a corresponding notch352 of inner core 324 when hollow structure 320 is filled with innercore material 326. In alternative embodiments, hollow structure 320 isformed in any suitable fashion that enables hollow structure 320 tofunction as described herein.

FIG. 10 is a schematic perspective cutaway view of three additionalembodiments of jacketed core 310 for use with mold assembly 301 (shownin FIG. 3). In each embodiment, jacketed core 310 is formed from hollowstructure 320 having interior portion 360 shaped to define at least oneinterior passage feature 98 of internal passage 82 (shown in FIG. 2). Inparticular, interior portion 360 is shaped to define at least onecomplementary feature 331 of inner core 324. In the first embodiment,shown on the left in FIG. 10, interior portion 360 of hollow structure320 is shaped to define sharp-edged bead-type turbulators withininternal passage 82. Correspondingly, interior portion 360 is shaped todefine complementary features 331 of inner core 324 as sharp-edged beadstructures 335 when inner core material 326 is added to hollow structure320. In the second embodiment shown in the middle in FIG. 10, interiorportion 360 of hollow structure 320 is shaped to define smooth-edgedbead-type turbulators within internal passage 82. Correspondingly,interior portion 360 is shaped to define complementary features 331 assmooth-edged bead structures 337 when inner core material 326 is addedto hollow structure 320. In the third embodiment shown on the right inFIG. 10, interior portion 360 of hollow structure 320 is shaped todefine rifled grooves along internal passage 82. Correspondingly,interior portion 360 is shaped to define complementary features 331 ofinner core 324 as rifled groove structures 339 when inner core material326 is added to hollow structure 320.

In certain embodiments, hollow structure 320 is formed using a suitableadditive manufacturing process. For example, hollow structure 320extends from a first end 362 to an opposite second end 364, and acomputer design model of hollow structure 320, including the structureof interior portion 360, is sliced into a series of thin, parallelplanes between first end 362 and second end 364. A computer numericallycontrolled (CNC) machine deposits successive layers of first material322 from first end 362 to second end 364 in accordance with the modelslices to form hollow structure 320. Three such representative layersare indicated as layers 366, 368, and 370. In some embodiments, thesuccessive layers of first material 322 are deposited using at least oneof a direct metal laser melting (DMLM) process, a direct metal lasersintering (DMLS) process, and a selective laser sintering (SLS) process.Additionally or alternatively, the successive layers of first material322 are deposited using any suitable process that enables hollowstructure 320 to be formed as described herein.

In some embodiments, the formation of hollow structure 320 by anadditive manufacturing process enables interior portion 360 of hollowstructure 320 to be formed with a structural intricacy, precision,and/or repeatability that is not achievable by adding the structure ofinterior portion 360 to a preformed straight tube 319 (shown in FIG. 7).Accordingly, the formation of hollow structure 320 by an additivemanufacturing process enables the shaping of complementary features 331of inner core 324, and thus of interior passage features 98 of internalpassage 82, with a correspondingly increased structural intricacy,precision, and/or repeatability. Additionally or alternatively, theformation of interior portion 360 of hollow structure 320 during anadditive manufacturing process enables the subsequent complementaryformation of interior passage features 98 at locations along internalpassage 82 that could not be reliably added to internal passage 82 in aseparate process after initial formation of component 80 in mold 300, asdiscussed above.

Alternatively, in some embodiments, hollow structure 320 is at leastpartially formed by adding at least one bulged region 344 to aninitially straight tube, such as straight tube 319 (shown in FIG. 7).For example, but not by way of limitation, the at least one bulgedregion 344 is formed by one of mechanical ram expansion and hydroformingof hollow structure 320. Bulged regions 344 shape interior portion 360of hollow structure 320 to define at least one complementary feature 331of inner core 324 as at least one bulged feature 343. For example, in anembodiment, smooth-edged bead structures 337 shown in the middleembodiment in FIG. 10 are formed as bulged features 343 complementary tobulged regions 344 when inner core material 326 is added to hollowstructure 320. Bulged features 343 are shaped to define generallyrecessed passage wall features 98. For example, bulged features 343implemented as smooth-edged bead structures 337 are complementarilyshaped to define smooth-edged bead-type turbulators within internalpassage 82. Alternatively, bulged features 344 are shaped such thatinterior portion 360 of hollow structure 320 defines any suitablepassage wall feature 98 that enables internal passage 82 to function asdescribed herein.

FIG. 11 is a schematic cross-sectional side view of another exemplaryembodiment of hollow structure 320 for use in forming jacketed core 310for use with mold assembly 301 (shown in FIG. 3). FIG. 12 is a schematicfront cross-section view of the embodiment of hollow structure 320 shownin FIG. 11, taken along lines 12-12. As described above, hollowstructure 320 has outer wall 380 configured to enclose inner core 324(shown in FIG. 4) along a length of hollow structure 320. In theillustrated embodiment, outer wall 380 defines a generally constant,rectangular cross-sectional perimeter of hollow structure 320. Inalternative embodiments, outer wall 380 defines any suitablecross-sectional perimeter that enables jacketed core 310 to function asdescribed herein.

In certain embodiments, interior portion 360 of hollow structure 320defines a louver structure 371 shaped to define a louvered interiorpassage feature 98 of internal passage 82 (shown in FIG. 2). Forexample, in the illustrated embodiment, interior portion 360 defines aplurality of obliquely disposed convolution faces 372 that each extendfrom one of a plurality of peaks 374 to one of a plurality of valleys376. Peaks 374 and valleys 376 are defined on opposite sides of hollowstructure 320, such that each peak 374 and each valley 376 liesproximate outer wall 380 of hollow structure 320.

In the exemplary embodiment, each convolution face 372 includes aplurality of louvers 378. In certain embodiments, internal passage 82(shown in FIG. 2) is used for cooling purposes, and louvers 378 aresuitably arranged such that the corresponding louvered interior passagefeatures 98 defined thereby facilitate selected flow characteristics fora fluid within internal passage 82. For example, in the illustratedembodiment, louvers 378 on each convolution face 372 are spaced andangled such that the corresponding louvered interior passage features 98defined thereby facilitate thin film converging/diverging laminar flowconvection, while maintaining pressure loss through internal passage 82within an acceptable range. In alternative embodiments, convolutionfaces 372 each have any suitable structure that enables hollow structure320 to function as described herein.

In certain embodiments, hollow structure 320 is again formed using asuitable additive manufacturing process, in which, for example, a CNCmachine deposits successive layers of first material 322 from first end362 to second end 364 to form hollow structure 320. More specifically,the CNC machine deposits successive layers of first material 322 tosimultaneously form each successive layer, such as representative layer366, of outer wall 380 and interior portion 360. As described above,forming hollow structure 320 using a suitable additive manufacturingprocess enables forming interior portion 360 of hollow structure 320with a structural intricacy, precision, and/or repeatability that is notachievable using other methods. For example, in some embodiments,forming hollow structure 320 using a suitable additive manufacturingprocess enables interior portion 360 of hollow structure 320 to defineany of a variety of suitable louver configurations for heat transferapplications on a scale suitable for use as interior passage features 98in internal passage 82. In alternative embodiments, hollow structure 320is formed using any suitable process that enables hollow structure 320to function as described herein.

As described above, jacketed core 310 is formed by disposing inner corematerial 326 within hollow structure 320, such that inner core 324 iscomplementarily shaped by interior portion 360 of hollow structure 320.In particular, interior portion 360 defines complementary features 331of inner core 324 as a complement or “negative image” of louverstructure 371 of interior portion 360. Subsequently, during formation ofcomponent 80 in mold 300, molten component material 78 at leastpartially absorbs first material 322 from hollow structure 320,including from interior portion 360. For example, interior portion 360is formed from first material 322 and/or another suitable material thatis compatible with component material 78, and interior portion 360 issubjected to absorptive contact with component material 78 through peaks374 and valleys 376 after outer wall 380 is at least partially absorbed.Molten component material 78 couples against complementary features 331of inner core 324 to form louvered interior passage features 98 that areshaped substantially identically to louver structure 371 of interiorportion 360 of hollow structure 320.

With reference to FIGS. 5-12, although the illustrated embodiments showinterior portion 360 of hollow structure 320 configured to definecomplementary features 331 of inner core 324 as recessed features 334,dimple imprints 333, sharp-edged bead structures 335, smooth-edged beadstructures 337, rifled groove structures 339, and the complement oflouver structure 371 to define a shape of interior passage features 98,it should be understood that this disclosure contemplates interiorportion 360 of hollow structure 320 configured to define complementaryfeatures 331 having any suitable additional or alternative shape thatenables inner core 324 to function as described herein. Moreover,although the illustrated embodiments show each embodiment of interiorportion 360 of hollow structure 320 configured to define inner core 324as having complementary features 331 of a substantially identicalrepeating shape, it should be understood that this disclosurecontemplates interior portion 360 of hollow structure 320 configured todefine inner core 324 having any suitable combination of differentlyshaped complementary features 331 that enables inner core 324 tofunction as described herein.

With further reference to FIGS. 5-12, although the illustratedembodiments show inner core 324 as having a generally circular, ovoid,tapered, or rectangular cross-sectional perimeter, it should beunderstood that inner core 324 has any suitable additional oralternative cross-sectional perimeter that enables inner core 324 tofunction as described herein. Moreover, although the illustratedembodiments show each embodiment of inner core 324 as having a generallyconstant pattern of cross-sectional perimeter along its length, itshould be understood that inner core 324 has any suitable variation incross-sectional perimeter along its length that enables inner core 324to function as described herein.

An exemplary method 1300 of forming a component, such as component 80,having an internal passage defined therein, such as internal passage 82,is illustrated in a flow diagram in FIGS. 13 and 14. With reference alsoto FIGS. 1-12, exemplary method 1300 includes positioning 1302 ajacketed core, such as jacketed core 310, with respect to a mold, suchas mold 300. The mold defines a cavity therein, such as mold cavity 304.The jacketed core includes a hollow structure, such as hollow structure320, that includes an interior portion, such as interior portion 360,shaped to define at least one interior passage feature of the internalpassage, such as interior passage feature 98. The jacketed core alsoincludes an inner core, such as inner core 324, disposed within thehollow structure and complementarily shaped by the interior portion ofthe hollow structure. Method 1300 also includes introducing 1304 acomponent material, such as component material 78, in a molten stateinto the cavity to form the component, such that the inner core definesthe internal passage including the at least one interior passage featuredefined therein.

In certain embodiments, method 1300 further includes, prior to disposingthe inner core material within the hollow structure, pre-forming 1306the interior portion of the hollow structure such that the interiorportion is shaped to define a selected shape of the at least oneinterior passage feature. In some such embodiments, the step ofpre-forming 1306 the interior portion of the hollow structure includescrimping 1308 the hollow structure at a plurality of locations to definea plurality of indentations, such as indentations 340. The indentationsare shaped to define the at least one interior passage feature when thecomponent is formed. Additionally or alternatively, the step ofpre-forming 1306 the interior portion of the hollow structure includesusing 1310 a suitable tube press. In some such embodiments, the step ofusing 1310 the tube press further includes bending 1312 the hollowstructure to match a preselected nonlinear shape of the internalpassage. Additionally or alternatively, the step of using 1310 the tubepress further includes forming 1314 a non-circular cross-sectionalperimeter of at least a portion of the hollow structure corresponding toa selected non-circular cross-sectional perimeter of at least a portionof the internal passage.

In some embodiments, the step of pre-forming 1306 the interior portionof the hollow structure includes forming 1316 the hollow structure usingan additive manufacturing process. In some such embodiments, the step offorming 1316 the interior portion of the hollow structure includes using1318 at least one of a direct metal laser melting (DMLM) process, adirect metal laser sintering (DMLS) process, and a selective lasersintering (SLS) process.

In certain embodiments, the step of positioning 1302 the jacketed coreincludes positioning 1320 the jacketed core that includes a plurality ofindentations, such as indentations 340, defined on the hollow structureand shaped to define the at least one interior passage feature as aplurality of ridges, such as those defined by recessed features 334.Additionally or alternatively, the step of positioning 1302 the jacketedcore includes positioning 1322 the jacketed core that includes aplurality of indentations, such as indentations 340, defined on thehollow structure and shaped to define the at least one interior passagefeature as a plurality of dimples, such as dimples formed by dimpleimprints 333. Additionally or alternatively, the step of positioning1302 the jacketed core includes positioning 1324 the jacketed core thatincludes the interior portion of the hollow structure shaped to definethe at least one interior passage feature as at least one of asharp-edged bead, a smooth-edged bead, and a rifled groove, such asthose defined respectively by sharp-edged bead structures 335,smooth-edged bead structures 337, and rifled groove structures 339.

In some embodiments, the step of positioning 1302 the jacketed coreincludes positioning 1326 the jacketed core that includes the interiorportion of the hollow structure shaped to define the at least oneinterior passage feature as at least one louvered interior passagefeature, such as one defined by louvered structure 371. In some suchembodiments, the step of positioning 1302 the jacketed core includespositioning 1328 the jacketed core that includes the interior portionthat defines a plurality of obliquely disposed convolution faces, suchas convolution faces 372. Each convolution face includes a plurality oflouvers, such as louvers 378. Moreover, in some such embodiments, thestep of positioning 1302 the jacketed core includes positioning 1330 thejacketed core that includes the interior portion that defines each ofthe convolution faces extending from one of a plurality of peaks to oneof a plurality of valleys of the louver structure, such as peaks 374 andvalleys 376. The peaks and the valleys are defined on opposite sides ofthe hollow structure such that each of the peaks and the valleys liesproximate an outer wall, such as outer wall 380, of the hollowstructure.

In certain embodiments, the step of positioning 1302 the jacketed coreincludes positioning 1332 the jacketed core that includes the interiorportion of the hollow structure shaped to define at least onecomplementary feature of the inner core, such as the at least onecomplementary feature 331. The at least one complementary feature of theinner core couples against the component material in the molten state toshape the at least one interior passage feature.

The above-described jacketed core provides a cost-effective method forforming components that include internal passages defined therein withinterior passage features, while reducing or eliminating fragilityproblems associated with the core. Specifically, the jacketed coreincludes the inner core, which is positioned within the mold cavity todefine the position of the internal passage within the component, andalso includes the hollow structure within which the inner core isdisposed. The inner core is complementarily shaped by an interiorportion of the hollow structure, such that the inner core defines atleast one interior passage feature within the internal passage. Inparticular, but not by way of limitation, the jacketed core and methodsdescribed herein enable a reliable and repeatable formation of interiorpassage features at any location within internal passages havingnonlinear and/or complex shapes and/or characterized by high L/d ratios.Also, specifically, the hollow structure is formed from a material thatis at least partially absorbable by the molten component materialintroduced into the mold cavity to form the component. Thus, the use ofthe hollow structure does not interfere with the structural orperformance characteristics of the component, and does not interferewith the later removal of the inner core material from the component toform the internal passage.

In addition, the jacketed core described herein provides acost-effective and high-accuracy method to integrally form interiorpassage features of increased detail and/or complexity in the internalpassage. Specifically, in some embodiments, the hollow structurereinforces the inner core, such that a risk of cracking of the innercore proximate stress concentrations associated with a complementaryfeature-forming geometry of the inner core is reduced. Additionally oralternatively, the ability to pre-shape the hollow structure to definethe inner core facilitates adding complementary features to the innercore without machining the inner core, thus avoiding a risk of crackingor damaging the core.

An exemplary technical effect of the methods, systems, and apparatusdescribed herein includes at least one of: (a) reducing or eliminatingfragility problems associated with forming, handling, transport, and/orstorage of the core used in forming a component having an internalpassage defined therein, the internal passage having interior passagefeatures; (b) an ability to reliably and repeatably form interiorpassage features at any location within internal passages, even thosehaving nonlinear and/or complex shapes and/or characterized by high L/dratios; and (c) reducing or eliminating fragility problems associatedwith features of the core that complementarily define interior passagefeatures in the component.

Exemplary embodiments of jacketed cores are described above in detail.The jacketed cores, and methods and systems using such jacketed cores,are not limited to the specific embodiments described herein, butrather, components of systems and/or steps of the methods may beutilized independently and separately from other components and/or stepsdescribed herein. For example, the exemplary embodiments can beimplemented and utilized in connection with many other applications thatare currently configured to use cores within mold assemblies.

Although specific features of various embodiments of the disclosure maybe shown in some drawings and not in others, this is for convenienceonly. In accordance with the principles of the disclosure, any featureof a drawing may be referenced and/or claimed in combination with anyfeature of any other drawing.

This written description uses examples to disclose the embodiments,including the best mode, and also to enable any person skilled in theart to practice the embodiments, including making and using any devicesor systems and performing any incorporated methods. The patentable scopeof the disclosure is defined by the claims, and may include otherexamples that occur to those skilled in the art. Such other examples areintended to be within the scope of the claims if they have structuralelements that do not differ from the literal language of the claims, orif they include equivalent structural elements with insubstantialdifferences from the literal language of the claims.

What is claimed is:
 1. A method of forming a component having aninternal passage defined therein, said method comprising: positioning ajacketed core with respect to a mold, wherein the jacketed coreincludes: a hollow structure formed from a first material that extendsfrom an interior portion of the hollow structure to substantially anentire outer perimeter of the hollow structure, wherein the interiorportion is shaped to define at least one interior passage feature of theinternal passage, and wherein the first material is metallic; and aninner core disposed within the hollow structure and complementarilyshaped by the interior portion of the hollow structure; introducing acomponent material in a molten state into a cavity of the mold, suchthat a portion of the jacketed core is submerged, and such that thecomponent material in the molten state contacts the first material alongsubstantially the entire outer perimeter of the submerged portion of thejacketed core to form the component, such that the inner core definesthe internal passage including the at least one interior passage featuredefined therein; cooling the component material in the cavity to formthe component; and removing the inner core from the component to formthe internal passage.
 2. The method of claim 1, further comprising,prior to disposing an inner core material within the hollow structure,pre-forming the interior portion of the hollow structure such that theinterior portion is shaped to define a selected shape of the at leastone interior passage feature.
 3. The method of claim 2, wherein saidpre-forming the interior portion of the hollow structure comprisescrimping the hollow structure at a plurality of locations to define aplurality of indentations, the indentations shaped to define the atleast one interior passage feature when the component is formed.
 4. Themethod of claim 2, wherein said pre-forming the interior portion of thehollow structure comprises using a tube press.
 5. The method of claim 4,wherein said using the tube press further comprises bending the hollowstructure to match a preselected nonlinear shape of the internalpassage.
 6. The method of claim 4, wherein said using the tube pressfurther comprises forming a non-circular cross-sectional perimeter of atleast a portion of the hollow structure corresponding to a selectednon-circular cross-sectional perimeter of at least a portion of theinternal passage.
 7. The method of claim 2, wherein said pre-forming theinterior portion of the hollow structure comprises forming the hollowstructure using an additive manufacturing process.
 8. The method ofclaim 7, wherein said forming the hollow structure comprises using atleast one of a direct metal laser melting (DMLM) process, a direct metallaser sintering (DMLS) process, and a selective laser sintering (SLS)process.
 9. The method of claim 1, wherein said positioning the jacketedcore comprises positioning the jacketed core that includes a pluralityof indentations defined on the hollow structure, the indentations shapedto define the at least one interior passage feature as a plurality ofridges.
 10. The method of claim 1, wherein said positioning the jacketedcore comprises positioning the jacketed core that includes a pluralityof indentations defined on the hollow structure, the indentations shapedto define the at least one interior passage feature as a plurality ofdimples.
 11. The method of claim 1, wherein said positioning thejacketed core comprises positioning the jacketed core including theinterior portion of the hollow structure shaped to define the at leastone interior passage feature as at least one of a sharp-edged bead, asmooth-edged bead, and a rifled groove.
 12. The method of claim 1,wherein said positioning the jacketed core comprises positioning thejacketed core including the interior portion of the hollow structureshaped to define the at least one interior passage feature as at leastone louvered interior passage feature.
 13. The method of claim 12,wherein said positioning the jacketed core comprises positioning thejacketed core including the interior portion that defines a plurality ofobliquely disposed convolution faces, wherein each convolution faceincludes a plurality of louvers.
 14. The method of claim 13, whereinsaid positioning the jacketed core comprises positioning the jacketedcore including the interior portion that defines each of the convolutionfaces extending from one of a plurality of peaks to one of a pluralityof valleys of the louver structure, the peaks and the valleys defined onopposite sides of the hollow structure such that each of the peaks andthe valleys lies proximate the outer perimeter of the hollow structure.15. The method of claim 1, wherein said positioning the jacketed corecomprises positioning the jacketed core including the interior portionof the hollow structure shaped to define at least one complementaryfeature of the inner core, wherein the component material in the moltenstate couples against the at least one complementary feature of theinner core to shape the at least one interior passage feature.